I've finally managed to sit down and write a few lines of code to make our old friend the DDC118 work. The main bug in the PCB design is that the analog supply voltage was designed to run at 3.3V (where it should have been 5.0V). The direct connection to the USB 5V in conjunction with some other effects appear to cause some minor noise issues.
Below I'd like to share the colorful plot of my finger swiping across the exposed input pads in a / \ / pattern. Sorta works. Now for some clean-up...
I've added the demo code to the project. The DDC interface is pretty straight forward, I'll have to give the byte chunk paritioning a good look though.
As you may tell there's a problem with the byte ordering. This is fixed later (endianness).